Cancer is a major global problem. There are about 1.7 million of new cancer cases and about 580,000 deaths from cancer in the United States every year amounting to one in 4 deaths is due to cancer. Cancer can impact all organs and systems in the body including, but not limited to the genital system, which includes the prostate, the digestive system which includes the colon and the pancreas, the respiratory system that includes the lung and bronchus, the breast, the urinary system that includes bladder renal and kidney, the skin, blood such as (lymphoma, leukemia, myeloma), endocrine, oral cavity and pharynx, brain, soft tissue, bones, joints and eye (Siegel, R. et al., CA Cancer J. Clin. 2013, 63, 11-30).
The human genome encodes for 518 protein kinases of which 30 distinct targets have been developed in the clinic primarily for the treatment of cancer. However, deregulation of kinase functions has also been implicated in immunological diseases and disorders, neurological diseases and disorders, metabolic diseases and disorders and infectious disease. The utility of kinases as drug targets is driven by several factors which include their involvement in signal transduction pathways that are dependent on a phosphotransfer cascade to elicit a real physiological response (Zhang, J. et al., Nature, 2009, 9, 28-39). Approximately 100 are tyrosine kinases. These kinases regulate several physiological mechanisms including but not limited to cell proliferation, cell differentiation, cell migration, and cellular metabolism by transferring the ATP terminal phosphate to one or more tyrosine or serine residues of the protein substrates (Carmi, C. et. al., Biochem. Pharmcol. 2012, 84, 1388-1399).
The ErbB family of receptor tyrosine kinases and their ligands are important regulators of tumor cell proliferation, tumor angiogenesis and metastasis. (Gschwind, A. et. al., Nat. Rev. Cancer, 2004, 4, 361). There are four receptors in the ErbB family, EGFR (endothelial growth factor receptor), HER2, HER3 and HER4. EGFR plays a key role in signal transduction pathways controlling proliferation and apoptosis (Zhou, B-B S. et. al. Cancer Cell, 2006, 10, 39-50). Activation of the EGFR pathway results in downstream events stimulating five of the six hallmarks of cancer: 1) independence of growth signals 2) insensitivity to growth-inhibitory signals 3) resistance to apoptosis, 4) angiogenesis, and 5) metastasis. Thus, inhibition of EGFR signaling presents multiple opportunities for identifying novel therapeutic agents.
The identification of somatic mutations in the tyrosine kinase domain of EGFR resulted in ligand-independent gene activation that are associated with responses to small molecule inhibitors of EGFR. The vast majority of EGFR mutations (>90%) are either a deletion of a conserved sequence in exon 19 or a single point mutation in exon 21 at amino acid residue 858 (L858R) (Lynch, T. J. et. al. N. Engl. J. Med. 2004, 350, 2129-39; Paez, J. G. et. al. Science (Wash. D.C.), 2004, 304, 1497-50; Kosaka, T. et. al. Cancer Res. 2004, 64, 8919-23). These activating mutations result in ligand-independent tumor-cell dependence on EGFR signaling and simultaneously provide the means to inhibit the tumor growth and cancer progression. EGFR mutations are most common in non-smoking East Asian females and those with adenocarcinoma histology. Although other point and deletion mutations have been discovered, only two mutations, deletion in exon 19 and L858R mutation in exon 21, account for over 90% of all mutations. The frequency of mutations in Asia is estimated to be approximately 35%, almost 4 times that of the U.S.A.
There are two main types of inhibitors of receptor tyrosine kinases that have potential benefit for treatment of EGFR dependent tumors. The ATP competitive inhibitors which are reversible and have broad pan ErbB family activity particularly as EGFR and HER2 inhibitors. Non-ATP competitive inhibitors are either lysine-trapping or cysteine-trapping covalent inhibitors and have attracted intensive investigations (Barf, T. et. al. J. Med. Chem., 2012, 55, 6243-6262). The latter non-ATP class includes two sub classes: pan ErbB inhibitors such as neratinib, afatinib and pelitinib, or inhibitors with high activities against mutant EGFR enzymes compared to wild type enzymes such as mereletinib (Butterworth, S. et. Al. PCT Int. Appl. (2013), WO 2013014448 A1 20130131) and rociletinib as well as a few as multicomponent inhibitors with proapoptotic effects (Antonello, A. et. al. J. Med. Chem., 2005, 48, 28-31 ibid J. Med. Chem., 2006, 49, 6642-6645). Gefitinib and erlotinib are the leading drugs as targeted agents inhibiting EGFR. Initially, gefitinib was approved as third-line therapy and in 2009 was granted European approval in EGFR-mutated NSCLC. Both drugs are now used as first-line therapy although gefitinib has superior tolerability and lower cost. Erlotinib is well positioned globally in maintenance therapy or refractory setting. Afatinib was approved in 2013 for late stage (metastatic) non-small cell lung cancer (NSCLC) patients whose tumors express specific types of epidermal growth factor receptor (EGFR) gene mutations, as detected by an FDA-approved test. Neratinib, AZD9291, and CO-1686 are also advancing in various clinical trials stages (Zhang, J. et. al. Nature, 2009, 9, 28-39; Bikker, J. et. al. J. Med. Chem. 2009, 52, 1493-1509).
Lung cancer is a disease in which the cell lining of lung tissue grows beyond control and leads to the formation of tumors. There are two main types of lung cancer; small cell lung cancer (SCLC) that accounts for about 15-20% of the total lung cancers and non-small cell lung cancer (NSCLC) that accounts for the rest. The common cause of lung cancer is exposure to tobacco smoke. Small cell lung cancer has very high metastasis and hence is inoperable. The survival rate for such a cancer is very low after diagnosis and has the highest mortality rate of all cancers. NSCLC is further categorized depending on the cell structure. It consists primarily of three types: 1) squamous cell carcinoma affecting the squamous epithelium, 2) adenocarcinoma affecting the glandular epithelium, and 3) the large cell carcinoma which is a heterogeneous group of neoplasm affecting the epithelial lining of the lung.
Non-small cell lung cancer is the most common type of lung cancer accounting for about 80-85% of all the lung cancers. The growth of this cancer is slower as compared to SCLC. Each type of NSCLC has different cancer cells and hence they grow and spread in different ways. The squamous cell cancer is the cancer of the squamous cells (thin and flat cells), accounting for about 30% of all NSCLC; adenocarcinoma is most common subtype of NSCLC, which develops at the edge of the lungs and in the cells in the airway, the most common type in never-smokers, having slow growth and does not typically cause symptoms in the early stages. The non-squamous cell cancers (large cell+adenocarcinomas) account for 40% of all lung cancers or about 50% of NSCLC (Siegelin, M. D. Laboratory Investigation, 2014, 94, 129-137). Cancers of the lung are aggressive and treatment remains a significant challenge. The estimated number of new cases of lung cancer in the U.S.A. is about 228,190 cases in 2013 in both male and female (Siegel, R. et. al. CA Cancer J. Clin. 2013, 63, 11-30). This is about 13% of all new cancer cases combined and estimated to be 1,660,290 in the U.S.A. which include prostate 239,590 and breast 232,340 cases. Lung cancer, however, has the highest mortality rate of all cancers.
There are mutations which have been identified in non-squamous NSCLC in three genes: EGFR, ALK and KRAS. The KRAS gene is downstream from EGFR and mutations in KRAS also conferred intrinsic resistance however, there are currently no drugs approved for KRAS mutations. The EML4-ALK fusion translocation oncogene carries a unique mutation resulting in maintenance of the malignant behavior of cancer cells. About 3-7% of all NSCLC patients carry this mutation (10-20% in adenocarcinomas). Crizotinib is an approved drug for the treatment of ALK+NSCLC. Analysis of Crizotinib treated ALK+ patients indicated that 50% of patients had ALK-dominant mutations while the rest were non-dominant mutations of which 31% were activating EGFR or KRAS mutations. These data suggest that one third of patients' resistance to Crizotinib would likely respond to EGFR or KRAS therapy (Kibble, A. et. al. Thompson Reuters report Spotlight on non-small-cell lung cancer: a new era in personalized care, 2013).
The majority of NSCLCs are diagnosed in patients with either localized advanced stage III (30-40%) or metastatic stage IV (40%) disease and will require some form of chemotherapy. Only a minority of NSCLCs are diagnosed when the disease is still in its localized early stages thus limiting the use of curative therapy such as surgery or radiation. Although the one-year survival rates for advanced NSCLC are about 40-45%, the five-year survival rate is less than 15%. A significant proportion of patients with lung cancer have an EGFR mutation: about 15% in the West and 30-40% in Asia.
Disease progression typically indicates that 50-70% of NSCLC patients will receive second-line therapy and about 25-30% will receive third-line regimen. For patients harboring EGFR or ALK mutations, the market is currently served by gefitinib, erlotinib, afatinib (EGFR) and crizotinib (ALK) agents. Gefitinib and erlotinib have moved into first-line therapy in patients with known EGFR mutations, although about 60% of these patients develop resistance to these drugs. The T790M mutation renders these drugs ineffective and occurs in about 50% of the mutant EGFR after treatment of gefitinib and erlotinib. There is, therefore, a need to develop novel therapeutic agents that are active against mutant EGFR especially the exon 19 and exon 21 mutations. There is also an unmet medical need to treat NSCLC disease and other EGFR associated pathological states effectively and without adverse side effects.
EGFR is dysregulated in glioblastoma multiforme in addition to various tumors such as NSCLC, ovarian and breast cancers. In malignant neoplasms such as glioblastoma (GBM) which is the most common primary central nervous system tumor in adults, EGFR is overexpressed in about 40-50% of cases and almost 25% co-express the mutant EGFR subtype EGFRvIII (Loew, S. et. al. Anti-Cancer Agents Med. Chem., 2009, 9, 703-715). This mutant is highly oncogenic and is generated from a deletion of exons 2 to 7 of the EGFR gene resulting in an in-frame deletion of 267 amino acids (Hatanpaa, K. J. et. al. Neoplasia, 2010, 12, 675-684). Studies of the activation of signaling events in GBM tumor cells revealed notable differences between wild type and EGFR mutant expressing cells. The wild-type EGF receptor signals through its canonical pathways whereas tumors expressing the mutant EGFR do not use these pathways suggesting a different role of mutant EGFR in GBM tumor biology (Zhu, H. et. al. Proc. Natl. Acad. Sci. U.S.A. 2009, 1-5, 5).
Mutant EGFR plays a role in resistance to EGFR tyrosine kinase inhibitors (TKIs). Analysis of samples of patients with glioblastoma treated with EGFR TKIs demonstrate that tumor cells reversibly up regulate or suppress mutant EGFR expression and that resistance to TKIs occur after elimination of mutant EGFR from extrachromosomal DNA (Nathanson, D. A. et. al. Science, 2014, 343, 72-76).
Malignant peripheral nerve sheath tumors (MPNSTs) driven in part by hyperactive RAS and EGFR signaling are often incurable. In a specially developed xenografts model erlotinib demonstrated antiangiogenic effects suggesting the potential use of new TKIs in this model. The present invention provides methods to meet these critical needs.